import java.util.ArrayList;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User:
 * Date: 2024-09-01
 * Time: 19:10
 */
public class BinaryTree {
    static class TreeNode {
        public char val;
        public TreeNode left;//存储左孩子
        public TreeNode right;//存储右孩子

        public TreeNode(char val){
            this.val = val;
        }
    }



    public TreeNode createTree(){
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');

        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        E.right = H;
        C.left = F;
        C.right = G;

        return A;
    }

    //前序遍历
    void preOrder(TreeNode root){
        if(root == null){
           return;//执行返回，当root == null, 返回上一层
        }
        System.out.print(root.val + " ");
        postOrder(root.left);
        postOrder(root.right);
    }

    //遍历思路
    List<Character> list = new ArrayList<>();
    public List<Character> preorderTraversal(TreeNode root) {
        if(root == null){
            return list;
        }
        list.add(root.val);
        preorderTraversal(root.left);
        preorderTraversal(root.right);
        return list;
    }


    //子问题思路
    public List<Character> preorderTraversal2(TreeNode root) {
        List<Character> list = new ArrayList<>();
        if(root == null){
            return list;
        }
        list.add(root.val);

        List<Character> leftTree = preorderTraversal(root.left);
        list.addAll(leftTree);
        List<Character> rightTree = preorderTraversal(root.right);
        list.addAll(rightTree);

        return list;
    }
    //中序遍历
    void inOrder(TreeNode root){
        if(root == null){
            return;//执行返回，当root == null, 返回上一层
        }
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    //后序遍历
    void postOrder(TreeNode root){
        if(root == null){
            return;//执行返回，当root == null, 返回上一层
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }


    public static int nodeSize = 0;
    // 获取树中节点的个数
    public void size(TreeNode root){
        if(root == null){
            return ;
        }
        nodeSize++;
        size(root.right);
        size(root.left);

    }

    public int size2(TreeNode root){
        if(root == null){
            return 0;
        }
        return size2(root.left) + size2(root.right) + 1;
    }

    // 获取叶子节点的个数
    //遍历思路
    public static int leafSize = 0;
    public void getLeafNodeCount(TreeNode root){
        if(root == null){
            return ;
        }

        if(root.left == null && root.right == null){
            leafSize++;
        }
        getLeafNodeCount(root.left);
        getLeafNodeCount(root.right);

    }

    public int getLeafNodeCount1(TreeNode root){
        if(root == null){
            return 0;
        }
        if(root.left == null && root.right == null){
            return 1;
        }
        return  getLeafNodeCount1(root.left) +
                getLeafNodeCount1(root.right);
    }

    // 获取第K层节点的个数
    //子问题思路
    public int getKLevelNodeCount(TreeNode root,int k){
        if(root == null){
            return -1;
        }
        if(k == 1){
            return 1;
        }
        return  getKLevelNodeCount(root.left,k-1) +
                getKLevelNodeCount(root.right,k-1);
    }

    // 获取二叉树的高度
    //时间复杂度：O(N)
    //空间复杂度：O(logN)
    public int getHeight(TreeNode root){
        if(root == null){
            return 0;
        }
        int leftHeight = getHeight(root.left);
        int rightHeight = getHeight(root.right);

        return Math.max(leftHeight, rightHeight) + 1;
    }

    // 检测值为value的元素是否存在
    //时间复杂度：O(N)
    //空间复杂度：O(logN)
    public TreeNode findVal(TreeNode root, char val){
        if(root == null){
            return root;
        }
        if(root.val == val){
            return root;
        }
        TreeNode leftT =  findVal(root.left, val);
        if(leftT != null){
            return leftT;
        }

        TreeNode rightT =  findVal(root.right, val);
        if (rightT != null) {
            return rightT;
        }

        return null;
    }

   /* //层序遍历
    void levelOrder(TreeNode root){

    }

    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root){

    }*/
}


